The M-GAGE S18M sensor implements a passive sensing technology to detect large ferrous objects. The sensor measures the change in the Earth’s natural magnetic field (the ambient magnetic field) caused by the introduction of a ferromagnetic object.

This easy-to-use sensor is extremely robust and is unaffected by dirt and moisture, making it ideal for demanding outdoor environments. Simple programming procedures provide flexibility for a variety of applications.

Theory of Operation
The sensor uses three mutually perpendicular magnetoresistive transducers. Each transducer detects magnetic field changes along one axis. By incorporating three sensing elements, maximum sensor sensitivity is achieved.

A ferrous object will alter the local (ambient) magnetic field surrounding the object. The magnitude of this magnetic field change is dependent both on the object (its size, shape, orientation, and composition) and on the ambient magnetic field (its strength and orientation).

During a simple programming procedure, the S18M sensor measures the ambient magnetic field. When a large ferrous object (for example, a truck, automobile, or rail car) alters that magnetic field, the sensor detects the magnetic field changes (anomalies). When the degree of magnetic field change reaches the sensor’s threshold, the sensor’s discrete outputs switch.

Sensor Field of View and Range
The sensor range depends on three variables:
1. The local magnetic environment (including nearby ferrous material)
2. The magnetic properties of the object to be sensed
3. Sensor settings

The S18M can detect changes in the ambient magnetic field in all directions. As with other sensors, the range will depend on the target. The strong disturbance of a large ferrous object decreases as distance from the sensor increases, and the magnitude and shape of the disturbance is dependent on the object’s shape and content.

The sensor can be programmed to react to magnetic field disturbances of greater or lesser intensity, using two adjustments: background condition and sensitivity level. Once background condition and sensitivity level are set, and both settings are stored in non-volatile memory, the sensor is ready to detect the target object.

The Banner M-GAGE sensor can be used to trigger the opening and closing of high-traffic internal overhead doors. Mounted in the floor, it will reliably detect forklifts or trucks as they approach the doors. Banner’s applications engineers are available to help determine proper sensor placement for specific door-trigger applications.





For more information on this and other Sensing Products from Banner Engineering, contact your Great Lakes Automation Supply Sales Representative.